This dissertation covers several topics in macroeconomics. Chapter one provides an overview for this dissertation. Chapter two explores the role of demand shocks, as an alternative to productivity shocks, in driving both domestic and international business cycles. In addition to those well-documented domestic and international business cycle properties, this paper focuses on two additional stylized facts in the industrialized countries: procyclical trade openness (GDP fraction of trade volume) and countercyclical government size (GDP fraction of government spending). Using a parsimonious dynamic stochastic general equilibrium model, I show that the model's predictions under productivity shocks are not consistent with these facts. Instead, a...